As a magnetoresistive effect element which changes its electric resistance depending on a magnetic field, there has been known a TMR element (also referred to as an MTJ element) adapted to store information and to detect magnetism by using a TMR (tunnel magnetoresistance) effect. The use of the MTJ elements in MRAMs and the like has been expected in recent years.
Non Patent Document 1 discloses a perpendicular magnetization-type MTJ element. The perpendicular magnetization-type MTJ element includes a structure formed by stacking a free layer (a magnetization free layer), a tunnel barrier layer, and a reference layer (a magnetization fixed layer). Directions of magnetization of the free layer and the reference layer are made parallel to the stacking direction, respectively.
An increase in MR ratio (magnetoresistance ratio) is important for improving characteristics of an MRAM device using the magnetoresistive effect element. It is known that a stacking structure composed of CoFeB/MgO/CoFeB described in Non Patent Document 1 exhibits a high MR ratio above 100%.